In the food, beverage and dairy markets, a wide array of shelf stable packaged liquid and semi-liquid foods exist. Shelf stable foods are food products that have been processed so they can be safely stored and sold under non-refrigerated conditions in a sealed container while having a useful shelf life. These foods range from canned soups to highly acidified soda and sport drinks. Various techniques are used to produce shelf stable foods. One such technique is aseptic packaging. In a typical aseptic packaging procedure, a liquid food product is thermally sterilized while the food product packaging is separately chemically sterilized. The sterile food product and sterile packaging are then brought together and sealed under sterile conditions. This results in a shelf stable food product.
Chemical sterilization of the food product packaging is often performed in an aseptic packaging filler. Aseptic packaging fillers use a chemical sterilant to sterilize the food product packaging. Common aseptic fillers include a single-use filler and a re-use or recirculating filler. A single use filler uses a stock solution of sterilant. The filler deposits the sterilant on the inside and sometimes outside of packaging to sterilize it. The sterilant can be heated at the point of depositing or it can be pre-heated prior to depositing onto the packaging. Also, certain running conditions (e.g., temperature, contact time and concentration) are chosen so that the packaging is rendered commercially sterile. After being deposited inside of the packaging, the spent sterilant drains from the packaging and is exported by the filler either to a drain or to other parts of the machine for different treatments (such as treating an exterior of the packaging). In a single-use filler, once the sterilant is used, it is discarded.
A re-use or re-circulating filler contains a sump of sterilant. This sump is held at a desired temperature so that the sterilant is also maintained at a desired temperature. The filler draws sterilant from this sump and uses it to sterilize inside and/or outside of the food packaging. The sterilant then drains away from the packaging and it is collected and exported back to the same sump which it originated.
After the packaging is treated by either type of filler, it is rinsed with microbiologically pure water, filled with a food product and sealed. All of these steps occur under sterile conditions inside of the filler.
One commonly used chemical sterilant is a peracid solution. In this solution, peracid exists in equilibrium with its corresponding carboxylic acid and hydrogen peroxide. The equilibrium shifts to the reactant side or the product side of the chemical equilibrium equation based on the concentration of reactants or products present in a given solution.
Normally, a peracid solution is provided to an end-user as an equilibrium concentrate and the end-user dilutes the concentrate to the level that is required for microbial treatment of their surface of interest. When peracid solutions are used in a re-circulating filler, they are re-circulated back to a sump for extended periods of time. Over time, the peracid inside the sump slowly degrades or equilibrates back to the carboxylic acid and hydrogen peroxide. As a result, the sump accumulates higher levels of hydrogen peroxide and carboxylic acid. Filler operators have specifications set for maximum levels of hydrogen peroxide or carboxylic acid in the sump. When the sump approaches these maximum levels, the filler must be shut down, drained and refilled with fresh solution. Other filler operators set up fillers so that they have a certain bleed off rate. Adjusting the bleed off rate modifies the accumulation rate of peroxide and carboxylic acid in the sump so that the filler can be run for an extended length of time.
Additionally, other operators include catalase enzymes in the peracid solution, in order to reduce hydrogen peroxide in the solution. In such cases, operators must strictly monitor the hydrogen peroxide concentration and periodically add the enzymes into the solution when hydrogen peroxide reaches certain levels. The solution must also be provided at specific temperatures and within certain pH ranges in order for these enzymes to work.
Further, once the package is rinsed, e.g. with pure water, the rinse undesirably accumulates residues from the sterilant and is removed from the system.
All of these procedures unnecessarily increase the amount of water, energy, chemistry and complexity required to operate an aseptic filler. It is against this background that the present disclosure has been made.